Method of and apparatus for coating finely-divided particles



Aug. 27, 1929. 1,726,340

METHOD oF AND APPARATUS FOR Comm@ FINELY DIVIDED PARTICLES W. S; BUTTLES Filed han. 22, 1925 Patented Aug. 27, 1929..

:" U'NiTEfD s'ra'rus- 'PATENT-l. OFFICE..

WILLIAM STEVENS BUTTLES, OF CHICAGO, ILLDSI'OIS, ASSIGNOB T0 ELECTBIG COMPANY, INCORPORATED, F NEW YORK, N. Y., A COBPQBATION 0F NEW YORK. I

METHOD or'nm Arrmrus For. -coarme FmsLY-Drvmmi manoirs.

Application mea January a2, i925; serial no. aars.

This invention relates to methods of and apparatus lfor vcoating finely divided' particles, and has for its primary object, the provision of improved methods of and apinexpensive and effective in operation. y

In the embodiment illustrated herein, the apparatus is especially designed fo'r coating magnetic particles with zinc for use inthe manufacture of magnetic cores -used in loadying coils in accordance with Patent No.4

' C. Woodruff.

vthe method may be practiced, and in which 1,292,206, issued January 21, 1919 to John According to thel main features of the present invention a relative movement is caused between finely divided particles, such as particles ofnhllagnetic materialJ pand`rela-. tive'lyYiiXed surfaces of a coating material,

' such as zinc, the particles becoming coated with zinc removed by .abrasion from the fixed surfaces thereof.

The invention will be more fully understood from the following description and the accompanyin drawings showing an apparatus embodying. the invention and by which Fig. 1 is a front elevation vof adrum, partly cut away to show the wound ribbon contained therein; l Fig. 2 is a section along the line 21-2 of 'Fig'. 1 showing vthe ribbon and the finely divided particles between the convolutions thereof, and f1 Fig. 3 is an enlarged elevation of a portion ofthe twisted ribbon used in -forming the windi w n It is believed that 'the method will 'be clearly understood from'a description of the apparatus by which' it may be practiced. Although specific reference will be made to likev numerals are employed to designate similar parts throughout the several views,

brackets and l1 support the ends of a.

drum, which drum consists of a cylindrical member vor casing 13, a removable cover 14, end plates and 16, andintegral with the end plates, trnnnions and 2 1, respectively, the trunnion 2Q being extended to form a shaft leading to a source of wer- (not shown by means of which the maybe l rotate Within the drum aA tube 25, secured by suitable bolts to the end lates 15 and 16, supports a zinc tape or rib on 26, preliminarily twisted and then wound .therearoundI spiralled zinc. I substantially i fills the cylinder 1 3 but provides space for' particles 27 of finely divided material be-- in a plurality of layers. The ribbon as shown in the dra tween the successive convolutions thereof.

When it is, desired -to coat the nely di- -vided particles thecover 14 is removed from 'the drum,A the particles deposited therein and i the shaft 20 and the drum carried thereby is l caused to rotate. As the drum rotates, the particles 27 are tumbled within the drum and caused to fall in serpentine or tortuous aths in contact with the surfaces of the twiste ribbon of zinc 26.

a portion of the zinc from the ribbon by abrasion and coats the particles thoroughly-.with the removed z inc.' The zinc ribbons are preferably in a soft or annealed condition when placed within the drum, but hard or semiannealed zinc may also be employed, depend- Iinoved andthe drum ,turned so that the' opening covered by the door is over a receptacle 30 to receive the coated particles.

y 'The engagement between .the particles and the zinc surfaces removes 'The method as brQught out in the descrip- 4 tion of the apparatus consists in removing portions of zinc from surfaces thereof -by abrasion caused by the relative movement of nelydivided magnetic material and rela tively large surfaces of metallic zinc, the zinc surfaces being held in relatively fixed positions or moved in a predetermined man- `ner. However, it is apparent that the method may be practiced by the use of other than the particular apparatus described herein. One advantage of the method and apparatus form# ing the present invention is that a relatively large surface of zinc is exposed to the action of the particles, and in addition thereto a Iar'ge relative movement takes place between the'two materials. Furthermore, since the surfaces of 'the coating material are fixed relatively tol the drum,there is no necessity 'I ofrsifting'the particles after they have'V been coated and the possibility of fine particles of metallic zinc remaining with the inely divided magnetic material is minimized.

What is claimed is: 4 Y 1. A method of coating a finely divided particle of a hard material with a softer ma' ,terial, which 'consists in causing ,the particle to traverse a serpentine path in engagement with surfaces of the coating material.

2; A method vof coating finely divided part ticles of a magnetic material with a non-magi l 2o containenand means netic material, which Vconsists, in depositing portions f the coating material -upon the particles by causing engagementpver a serpentine path between the materials during a relative movement between the 'particles and surfacesoi the coating material. 1"

3. In an apparatus for coating inely di vided particles with material, a movable for securing strips of coating material thereto to present relatively fixed surfaces to the particles duringthe movement of the container.

4. Inan apparatus for coating finely dividedparticles with material, a rotatable drum for tumbling the particles, and means for securing a ribbon of thevcoating material therein to rotate therewith, said ribbon prer 30' senting a pluralitybf surfaces for contact- .helical convolutions to 'path in frictinal contact therewith. l 7. A method of coating nely divided par# elongated strip .l my name this 7th day with the lparticles during-the tumbling operation. v

5. In an a paratus fior* coating finely difvided partie es with material, a rotatable drum for tumbling the particles, and means for securing a twisted ribbon ofthe coating material therein to rotate therewith, said ribbon being wound in a plurality of layers of guide lthe particles in serpentine paths incontact with surfaces of the ribbon during the tumbling operation.

6. A method of coating iincly ivided particles of a material with a softermaterial, v l.

'which consists in arranging a strip ofthe softer material in aspiral form, and causing the finely divided particles to impinge upon the spiral strip and to traversea serpentine the softer material, ar4 

